Ratios F_a,c/F_a,cs as a function of effective particle radius a_eff for an effective temperature of T_eff = 3000  K and the two different atmospheric temperatures: T_a = 160  K (upper diagram) and T_a = 273  K (lower diagram). Results are shown for different values of the optical depth τ in each diagram: τ = 0.5 (black line), τ = 4 (red line), and τ = 10 (blue line). Calculations using DISORT (two-stream methods) are denoted by solid lines (dashed lines).